Process of making benzanthrone



-- aiaaa. 26,1 21 I 151,6265392 LPUNIITLED STATES P T NT; OFFICE;

nonmt'r e oAswELL- Ann ELLswoR'rn'G. MA RsHALnfor WILMINGTON, DELAWARE,

ASSIGNORSTO E.- I. no Pour DE NEMOURS" & ooiuraiw; or" WILMINGTON, Darawane, A CORPORATION 01 DELA ARE, gnocnss'or niaxme'iinnzanrnnonn.Ito-Drawing. :"A 'nieation'meaam 31,1920. Serial no. 4m,'492.

This invention relates'to' theproduction The reduction of, theanthraq'uinone to 55' of benzanthrone, and comprises reducing ant-hranolcan be brought about wlth copper anthraquinone to anthranol in a mediumof powder, granulated tin, etc.,-but we consider concentrated sul huricacid, adding glycerol it advantageous to'use freshly precipitated 5 andwater to the'reactio'n mass, and-efi'ectcopper obtained for example, byprecipitaing condensation of the. g yc l." r a Solution of copper s p'anthranol to form benzanthrone. Copper repared by-this method has afine- In a process heretofore 'known of produ'cfnes's'of 00 mesh. v aingbenzanthrone, and similar to the one out Heretoforethe glycerol hasbeen added 10 li d above, the best yield obtainedhas been within arelativelyshort time after the addi- 9 concentrated sulphuric acid(93-"9570 about 74%. We have discovered that by tion of the reducingagent has been com- :05 carefully followin certain conditions ofopl'pleted, whereas we; have found it to b 'i a eration, a yield'obenzanthrone amounting; portant to stir the mixture, to which, all theto 89% may be obtained. copper has been-added, for three hours at. Ourinvention may be illustrated by the a teniperatureof 3842 C'., or atleast until following example. (the parts being by thevcop'per iscompletely diseolved'inthejsul weight) vPhulficacid solution.

Three parts of anthraquinone (96 '1O0% The uniform rateof temperatureincrease purity) are dissolved in about 44v parts of from 90 to 120after the introduction of the. glycerin-water mixture is also impor- HSO;);and to this solution are thenadded taut; and'if the maximum yieldis to [be about 2parts of freshly precipitated copper obtained, careshould be taken not to allow during one and one-half hours at 3842 C.the temperature. to rise above 120 or 121- [After all of. the copper hasbeen added the 0., for at a tempemture several degrees 2'5- reactionmixture is kept at a te1nperature higher sulph'onationwappears to takeplace of from about 38 to 42 C. until solution of to an-appreciableextent with a consequent v.

the copper in the sulfuric acid has reached detrimental efi'ect on theyield and on'the v completion, ordinarily about 3 hours. y quahty of'theproduct, g .i

' A mixture of about 4 parts of water and I We claim:- v I .p H 30 about4 parts of glycerol .is thenintroduced- A" processot producinbenz'anthrone' during hourinto the sulphuric .acid soluwhich comprisestreating anti raqui1'1onedis-.' 5

tion, during which addition the temperature --'solved: in concentratedsulphuricjacid with of the mass is allowed to rise to 'from aboutfreshly precipitated copper at a t einperature -90 C. The temperature isthen raised of about 38.42 (1', 'untils'olution-of the 3 in the clauseof one andAone-half hours from copper 1n the sulphuric acidis'substantially C. to 0., the heating preferably 'co'mp'l'ete, graduallyadding glycerol and I being carried out in such'a way that the water,and thengradua'lly ra1s1ng;the'temtemperature rises uniformly at therate of perature ofthesoliition to f'about. 120 C.

1 C. every three .minutes. The reaction and maintaining it atabout thispoint until a 4 mass, after reaching about 120 (1., is kept the reactionis completed.-. v v at 118120 C.v for from about'2 to 3 hours, 2. Aprocess of producin be nzanthrone 5 after which it is cooledto about 60C. and which comprises treati-ng ant raquinone disthendrowned in water,-and: the resulting solved in about 15.'times its weight ofconprecipitate filtered and washeduntil the centI-ated sulphuric acidwith-freshly pre-' 45 cake is free from acid. 1 cipitated copper 'at 'atemperature of about The crude benzanthrone is then purified by 38 42,"-'(l. until solution of the copper in boiling for about A of an hour withabout the sulphuric acid is substantially complete;

50 parts of 1% caustic soda solution, folgradually adding glycerolandwatergradlowed by filtering and washing. The light ually raising thetemperatureof the solution yellowish fgreen benzanthrone thus obtainedtoab'out 120 (land maintainingit atabout has a meltmg'point of -170" C.and conthis pointuntilthe reaction is' completed. 1'05 tains from about5 to 7% of a black residue 3. A process .of 'producin benzanthr oneinsoluble .in alcohol. The yield of benzan-\ whichcomprises treating antraquinone disthrone is 89% of that requiredbytheory solved inconcentrated sulphuric acid'with freshly precipitated copper at atemperature of about 3842 (1., until solution of the copper in thesulphuric acid is substantially complete, gradually adding a mixture ofglycerol and water while permitting the temperature to rise to about 85to 90 (1., then heating to cause an increase in 'tem erature at theuniform rate of about 1 every three minutes until the temperaturereaches about 120 (3., and maintaining the temperature at about thispoint until the reaction is completed. p

4. In the production of benzanthrone the step which comprises reducinganthraquinone dissolved in sulphuric acid of 93 9570 strength withfreshly precipitated copper While maintaining the temperature of thesolution between about 38 and 42 C. 5. In the production of benzanthrone.the steps which comprise dissolving 3 parts of anthraquinone in about'50 parts of. sulphuric acid containing from 93 to 95% H bO graduallyadding about. 2 parts of freshly precipitated copper in the course ofabout one and one-halfhours, While keeping tures. 1

ROBERT G. CASWELL. ELLSWORTH G. MARSHALL.

